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Sang-Han Lee Pavel P. Povinec Janine Gastaud Beniamino Oregioni Laurent Coppola Catherine Jeandel 《Journal of Oceanography》2009,65(3):397-406
Anthropogenic 90Sr, 239,240Pu and 241Am were used as tracers of water mass circulation in the Crozet Basin of the South Indian Ocean, represented by three main
water fronts—Agulhas (AF), Subtropical (STF) and Subantarctic (SAF). Higher 90Sr concentrations observed north of 43°S were due to the influence of AF and STF, which are associated with the south branch
of the Subtropical gyre, which acts as a reservoir of radionuclides transported from the North to the South Indian Ocean.
On the other hand, the region south of 43°S has been influenced by SAF, bringing to the Crozet Basin Antarctic waters with
lower radionuclide concentrations. The 238Pu/239,240Pu activity ratios observed in water and zooplankton samples indicated that, even 35 years after the injection of 238Pu to the Indian Ocean from the burn-up of the SNAP-9A satellite, the increased levels of 238Pu in surface water and zooplankton are still well visible. The radionuclide concentrations in seawater and their availability
to zooplankton are responsible for the observed 210Po, 239,240Pu and 241Am levels in zooplankton. 相似文献
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André Giret Sylvie Tourpin Sabine Marc Olivier Verdier Jean-Yves Cottin 《Comptes Rendus Geoscience》2002,334(7):481-488
Despite its small area (5.6 km2), the Penguins Island brings magmatic information concerning mantle geochemical heterogeneities in southwestern Indian Ocean. The volcanism that built the island was firstly associated with marine deposits, and secondly with aerial, giving then abundant volcanic breccias and lava flows. The rocks are weakly differentiated and result of magmatic fractionation from picritic to tephritic types. KAr ages are near 1.1 Ma. The magmatic source may be related to a HIMU reservoir or to EMI ± EMII ones, depending on the geochemical evidences that are taken into account. However, comparisons with the Marion Island, on the same oceanic plateau and far to the west, as well as with Kerguelen Islands, far to the east, suggest a very heterogeneous mantle source. To cite this article: A. Giret et al., C. R. Geoscience 334 (2002) 481–488. 相似文献
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《African Journal of Marine Science》2013,35(2):299-306
The Crozet Plateau is situated below typical high-nutrient, low-chlorophyll (HNLC) waters of the southern Indian Ocean. The area to the east of the Crozet Islands experiences high levels of surface productivity during the austral summer due to natural iron enrichment from terrestrial sources and favourable light conditions. The demersal scavenging fauna at two areas of contrasting productivity, to the east and south of the islands, were investigated using two landers equipped with baited cameras and traps. Five species of scavenging fish were observed along with five groups of invertebrates during a single deployment of the RObust BIOdiversity (ROBIO) lander. Further deployments of the Fish RESPirometry (FRESP) video lander yielded no additional scavenging fish species. A modelled arrival and departure curve for the abyssal grenadier Coryphaenoides armatus suggests a region of low food availability compared to other regions worldwide. The ROBIO-derived abundance estimate for C. armatus of 187 ind. km–2 is comparable with published trawl-derived estimates. Significantly more amphipods were collected to the south of the islands, which was subject to lower organic matter supply. Reasons for this are unknown but may be due to differing current direction/velocities, or increased fish predation at the enriched site. The numerically dominant amphipod species present was Paralicella caperesca, followed by Eurythenes gryllus and Orchomenella gerulicorbis. A further five species were observed in low numbers, some occurring only once. One, Paracallisoma sp. nov, was a new species. 相似文献
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Marie Noël Lance Barrett-Lennard Christophe Guinet Neil Dangerfield Peter S. Ross 《Marine environmental research》2009,68(4):196-202
Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs), are ubiquitous environmental contaminants of which significant concentrations are reported in upper trophic level animals. In 1998, we collected blubber biopsy samples (n = 11) from killer whales (Orcinus orca) inhabiting the coastal waters around Possession Island, Crozet Archipelago, southern Indian Ocean, for contaminant analyses. Despite inhabiting an isolated region far removed from industrial activities, these killer whales can presently be considered among the most PCB-contaminated cetaceans in the southern hemisphere, with concentrations ranging from 4.4 to 20.5 mg/kg lipid weight (lw). PCDD levels ranged from below the detection limit (5 ng/kg) to 77.1 ng/kg lw and PCDF levels from below the detection limit (7 ng/kg) to 36.1 ng/kg lw. Over 70% of our study animals had PCB concentrations which exceeded a 1.3 mg/kg PCB threshold established for endocrine disruption and immunotoxicity in free-ranging harbour seals, suggesting that organic contaminants cannot be ruled out as an additional threat to this declining population. 相似文献
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